Electro-optical device and an electronic apparatus

ABSTRACT

An electro-optical device that drives each of plural pixels individually arranged in two dimensions so as to display information, is provided with a group of pixels displaying the information within an effective display region among the plural pixels arranged in two dimensions. A group of plural pseudo-pixels that do not contribute to the display of the information are located adjacent to a group of pixels within the effective display region. A bank layer separates a pixel in the group of the plural pseudo-pixels from a pixel in the group of pixels in the effective display region, and shields light leaked from a space between pixels located adjacently each other within the effective display region.

This is a Continuation of application Ser. No. 11/158,095 filed Jun. 22,2005 which is a Division of application Ser. No. 10/308,012 filed Dec.3, 2002 (issued as U.S. Pat. No. 6,949,883). The disclosures of theprior applications are hereby incorporated by reference herein in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to electro optical devices, such as aliquid crystal display device or an organic EL display device. Morespecifically, the invention relates to an electro optical deviceprovided with a structure to enhance product precision of the device ina production process of the electro optical device.

2. Description of Related Art

The related art includes an active matrix drive system as a drive systemfor an electro optical device that is provided with a liquid crystalelement, an organic EL element, an electrophoresis element, or anelectron-releasing element.

In an electro optical device of active matrix drive system, pluralpixels are arranged in a matrix within a display panel. Each of pluralpixels is provided with a pixel circuit that includes an electro opticalelement and a drive transistor that supplies drive power to an electrooptical element. In addition, each of plural pixel circuits is arrangedat the intersection between a data line and a scanning line, asdisclosed in WO98/36407.

SUMMARY OF THE INVENTION

However, when various kinds of electronic apparatus, such as a cellularphone and a personal computer, are facilitated by installing an electrooptical device on their substrates, it sometime occurs that displayingon the display region becomes unclear depending on a color of aperipheral display region in the electronic apparatus.

In addition, when a functional layer, providing an electro opticalfunction on an effective display region of an electro optical device, isformed, uniformity of such layer deteriorates depending on a localizedenvironment or an atmosphere, if such functional layer is formed by aliquid phase process, such as an inkjet method (a method of discharginga droplet) or a gas phase process, such as evaporation method. As aresult, there is a problem of unevenness on displaying.

Therefore, the present invention provides an electro optical deviceovercoming the above-mentioned and/or other problems.

In order to address or achieve the above, a first exemplary electrooptical device of the present invention drives each of plural pixelsindividually arranged in two dimensions, so as to display information.The electro optical device includes a group of pixels displayinginformation within an effective display region among the plural pixelsarranged in two dimensions; a group of plural pseudo-pixels that do notcontribute to the display of information, being located adjacent to agroup of pixels within the effective display region; and a bank layerseparating a pixel in the group of the plural pseudo-pixels from a pixelin the group of the pixels in the effective display region, andshielding light leaked from a space between pixels located adjacent eachother within the effective display region.

A second exemplary electro optical device of the present inventionincludes a plurality of pixels and includes: a group of pixels within aeffective display region, of which brightness is set in response to adata signal and a group of pseudo-pixels, of which brightness does notdepend on the data signal.

According to the above-mentioned structure of the electro opticaldevice, when a layer is formed by using an inkjet method, a material isejected to form the layer in the display region after the amount ofejected ink is stabilized in the pseudo-pixels region so that it ispossible to form the group of pixels in the effective display regionwith the uniform and constant thickness.

Further, when the layer is formed by an evaporation method, anatmosphere or an existence density of a vaporized material is differentlocally so that the thickness of the layer including the pixel in theeffective display region is not constant. On the other hand, if thegroup of pseudo-pixels or the group of dummy pixel area is installed, afunctional layer including the pixel in the effective display region canbe formed by utilizing a portion where an atmosphere or an existencedensity of a vaporized material is uniformed.

In addition, the group of pseudo-pixels or the group of dummy pixels isutilized for various kinds of applications. For example, various kindsof drive circuits, such as a scanning line drive circuit or a data linedrive circuit, may be installed in the dummy pixel region. Under such astructure, a limited space can be effectively utilized.

It is preferable that the group of plural pseudo-pixels is located atleast on one side of the effective display region.

It is preferable that the group of plural pseudo-pixels is located withsandwiching the group of pixels in the effective display region.

It is further preferable that the group of plural pseudo-pixels islocated surrounding the group of pixels in the effective display region.

According to the above-mentioned structure, thickness uniformity of afunctional layer including the pixel in the effective display region canbe further enhanced. In addition, when an electronic apparatus providedwith the above mentioned electro optical device on its substrate ismanufactured, a group of pseudo-pixels or a group of dummy pixel areathat does not depend on an image displayed in an effective displayregion of an electro optical device can be installed, and a boundarybetween the above substrate and displayed image becomes clear since aregion to show a selected color appropriately is installed.

According to the above-mentioned electro optical device, it ispreferable that the bank layer makes the shape of the group of pixels inthe effective display region to be almost the same as the shape of thegroup of plural pseudo-pixels. According to such a structure, conditions(a thickness of an layer, for example) of pixels in the above-mentionedeffective display region can be the same condition of pixels in thegroup of pseudo-pixels or the group of dummy pixels area so that a pixelin the group of pseudo-pixels or the group of dummy pixel area can beexamined instead of examining pixels in the above-mentioned effectivedisplay region.

In the above-mentioned electro optical device, at least one ofstructural elements including each of the pixels of the effectivedisplay pixels group is provided with a functional layer that is formedby an inkjet method.

The structural element formed by the inkjet method can be an organic ELlayer, for example. Also, for example, a carrier injection layer and acarrier transportation layer, such as a positive hole injection layer, apositive hole transportation layer, an electronic injection layer or anelectronic transportation layer, may be formed by an inkjet method.

Further, the organic EL layer can be made, for example, of a highpolymer including a fluorene derivative or a phenylenevinylen-serieshigh polymer material.

In the above-mentioned electro-optical device, it is preferable that ahydrophilic control layer having affinity toward a liquid material usedin the inkjet method is contacted with the functional layer.

Further, when the above-mentioned electro-optical device is providedwith a bank layer separating each of pixels, it is preferable that thehydrophilic control layer is formed under the bank layer. If affinity ofthe bank toward a liquid material is lowered than that of a hydrophiliccontrol layer, electric contamination between pixels is controlled andelectric separation between pixels is achieved.

As the material of the bank layer and the hydrophilic control layer,polyimide of which surface is coated with fluorine and oxidized siliconlayer that is hydrophilic-processed with plasma treatment can be used,for example.

In the electro optical device, the thickness of a functional layerincluding pixels in the group of pseudo-pixels or an area of the dummypixels may be examined, and as the result of such examination, it may bedetermined whether a pixel located in the effective display region isacceptable or not.

In the electro optical device, the examination may be implemented byirradiating examination light onto the pseudo-pixel and detectingoptical luminescence thereby. Such examination is simple and easy, andmany electro optical devices can be examined within short time.

In the electro optical device, it is preferable that a circuitarrangement region be provided where a circuit is arranged at the lowerpart of the region of the group of the pseudo-pixels. According to thisstructure, a limited space can be effectively utilized.

As a circuit installed in the above-mentioned region for a circuitarrangement, a scanning line drive circuit, a data line drive circuit, adata handling circuit, an operational circuit can be used, for example.

The electro optical device can be used as a display panel of anelectronic device, such as a computer device, a mobile type telephonedevice, a digital camera, an electronic book device and a mobile typeinformation-processing device, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explaining the present invention;

FIG. 2 is an enlarged view of portion A shown in FIG. 1;

FIG. 3 is a sectional view of a constitutional example of the pixel 20in an effective display region and pseudo-pixel 30;

FIG. 4 is a schematic of another constitution of the pseudo-pixel 30;

FIG. 5 is a sectional view of another constitution of the pseudo-pixel30;

FIG. 6 is a schematic explaining another exemplary embodiment of thepresent invention;

FIG. 7 is a schematic of another exemplary embodiment of the presentinvention;

FIG. 8 is a schematic perspective view of a mobile type personalcomputer which is an exemplary electronic device that incorporates theinvention;

FIG. 9 is a schematic perspective view of a cellular phone provided withan electro optical device related to the present invention which is anexemplary electronic device that incorporates the invention;

FIG. 10 is a schematic perspective view of a digital camera providedwith the electro optical device related to the present invention whichis an exemplary electronic device that incorporates the invention;

FIG. 11 is a schematic perspective view of an electronic book which isan exemplary electronic device that incorporates the invention.

FIG. 12 shows a data line drive circuit between the dummy pixel area andthe substrate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An exemplary embodiment of the present invention is described referringto drawings hereafter.

FIG. 1 is a schematic showing the structure of a first exemplaryembodiment of the present invention. According to the present invention,a pseudo-pixel region 3 where pseudo-pixels 30 that do not contribute toan image display, is arranged on the periphery of an effective displaypixel region 2 where pixels are arranged to display an actual image inan display device 1. In the effective display pixel region 2, pluralpixels 20 are arranged in two dimensions to change optical parameterssuch as light intensity and the transmittance ratio in response toelectrical signals for image information. For example, each of pixels 20includes an organic EL light emission element, for example. Each layerof this organic EL light emission element is formed by applying amaterial via an inkjet method.

In the first exemplary embodiment, pseudo-pixels 30 are arranged in twodimensions on both sides of right and left area and upper and lower areaof the effective display region 2 with a shape of a pixel and a spacingbetween pixels, which are the same of the effective display pixel 20. Aninkjet head (not shown in FIG. 1) is scanned in the right and leftdirection 4 or the top and bottom direction 5 so as to eject a materialto form a layer. At this time, the inkjet head starts ejecting withinthis pseudo-pixel region 3 and then, forming a layer in an effectivedisplay pixel region 2 in a stable ejecting state. Namely, vacantejection, which does not contribute to form an affective pixel, iscompleted within the pseudo-pixel region 3 at the beginning of ejectingink (a material to form a layer) so as to stabilize the amount ofejected ink, and further vacant ink ejection is completed within thepseudo-pixel region 3 at the end of ejecting ink so as to prevent orreduce unevenness just before stopping the ejection. In the pseudo-pixelregion 3 of the present exemplary embodiment, it is not necessary tosupply a drive signal to pixel electrodes since they are not used forimage display. In addition, in a later example, a drive circuit is notconnected to a pixel with wiring. However, the shape of the pseudo-pixelis formed as the same shape of the effective pixel and a spacing andarrangement between the pseudo-pixels are the same spacing andarrangement between the effective pixels, since the amount of ejectionshould be stabilized as the same amount of ejection in the region of theeffective display pixels and timing of ejection should be synchronized.

FIG. 2 is an enlarged schematic showing a portion A (shown in FIG. 1) ina border between the effective display pixel region 2 and thepseudo-pixel region 3 of the display device 1.

The shape of the pseudo-pixel 30 in the pseudo-pixel region 3 and theeffective pixel 20 in the effective display pixel region 2 is arectangle or a substantial rectangle of which the four corners areround-shaped. As described above, the effective pixel 20 is connected toa transistor (TFT) and wiring to drive it. But, the pseudo-pixel 30 isnot connected to them.

FIG. 3 is a schematic cross-sectional view of the effective pixel 20 andthe pseudo-pixel 30 taken along the X-Y direction shown in FIG. 2. Asshown in FIG. 3, an under-protective layer 52 made of oxidized silicon(SiO2) or nitride silicon (Si Nx) is formed on a transparent substrate51, such as a glass or resin, in order to reduce or prevent an invasionof an alkali ion from the substrate 51. A semiconductor layer 53 isformed by accumulating silicon (Si) via a CVD method on this protectivelayer 52. This semiconductor layer 53 is annealed with a laser so as toform a polycrystalline layer by crystallization. Then, thissemiconductor layer 53 is patterned so as to form a TFT region.

Next, a gate insulation layer 54 is formed on the semiconductor layer 53and the under-protective layer 52 by accumulating oxide silicon, ofwhich material is TEOS and oxygen, via a CVD method. Further, a metal,such as aluminum, is accumulated as a gate metal and patterned to form agate electrode and a wiring 55. Oxide silicon is accumulated on thislayer via a CVD method so as to be an interlayer insulation layer 56. Acontact hole is opened in the interlayer insulation layer 56corresponding to a source and drain region of the TFT region and ametal, such as aluminum, is accumulated within it and patterned to formsource and drain electrodes and a wiring layer 57. Next, an interlayerinsulation layer 58 is formed by accumulating oxidized silicon via a CVDmethod. A contact hole is opened in the interlayer insulation layer 58so as to accumulate a transparent ITO (Indium Tin Oxide) layer 59. Thewiring layer 57 is connected to the ITO layer 59. The ITO layer 59 ispatterned so as to form a pixel electrode layer (an anode) 59. On thislayer, a hydrophilic control layer 60 is formed by accumulating oxidizedsilicon via a CVD method in order to enhance adhesiveness of an ink (amaterial for a layer) ejected by an inkjet method to the substrate. Thishydrophilic control layer 60 is patterned to open the region of theeffective pixels and expose the transparent electrode ITO layer 59.

Next, oxide silicon is accumulated by a CVD method and patterned so asto open the region of the effective pixel 20 and the pseudo-pixel 30 andform a bank 61 to avoid light leak and color mixture between pixels.

An organic EL light emission element is formed in the trench opened atthe bank 61 by an inkjet method. Namely, the inkjet head (not shown inFIG. 3) is moved relatively to scan each of openings of the bank 61 andeject a material to form a layer from a nozzle at the position oppositeto such opening. A predetermined amount of a material for a layer isejected to each of openings of the bank 61 within the region 2 of theeffective pixels 20 by starting ejection from the region of the pseudopixels 30. In addition, a material for a layer is ejected outside of theregion of the effective pixels 20 so that it is possible to supply apredetermined mount of a material for a layer to the final one ofeffective pixels 20.

At first, a positive hole transportation layer 62 is formed on the ITOlayer 59 exposed at the bottom of the trench in the bank 61 by an inkjetmethod. An end portion 60 a of the opening of the hydrophilic controllayer 60 is exposed at the bottom of the trench from the end portion 61a of the opening of the bank 61 so that a liquid material to form alayer ejected from the inkjet head, adapts the end portion 60 a of theopening of the hydrophilic control layer 60 and easily spreads to thebottom portion of the rectangular opening with uniformity. An organic ELlayer 63 is formed by an inkjet method on the positive holetransportation layer 62 formed on the ITO layer 59. An electronictransportation layer (not shown in FIG. 3) may further be formed on theorganic EL layer 63. Furthermore, a cathode layer 64 is formed as thecommon electrode on the organic EL layer 63 so as to obtain the displaydevice 1 where the organic EL emission light element is a unit pixel.Here, a conventional, related art or later developed drive circuit canbe used.

According to the first exemplary embodiment, the conductive ITO layer 59is not formed on the side of the pseudo-pixel 30. In this case, it isadvantageous in that yield is enhanced since the device (the pixel) hasan insulation against high voltage.

In addition, the region of the pseudo-pixel 30 is not used as actualdisplay pixels so that it is possible to install a part of a pixelcircuit to drive the effective pixel 20, a part of a scanning circuitand a data line drive circuit between the dummy pixel area and thesubstrate 51. As seen in FIG. 12, the data line/scanning line drivingcircuit 70 can be positioned between the substrate 1 and the dummy pixelarea 3. In this manner, the data line/scanning line driving circuit 70can at least partially overlap the group of dummy pixels.

FIG. 4 shows a second exemplary embodiment. The same reference numbersshown in FIG. 2 are referred to in FIG. 4 and explanation of them isomitted.

In this example, the ITO layer 59 and the hydrophilic control layer 60are also formed in the region 3 of the pseudo-pixel 30. Hence, a layer,which is the same of each of layers of the organic EL element, is formedin the pseudo-pixel 30 as the same process of forming each of layers ofthe organic EL element in the effective pixel 20. However, wiring to thepseudo-pixel is intercepted and it is not used as displaying of imageinformation. Further, it is possible to examine the uniformity of thelayer by irradiating examination light onto the illumination layer ofthe pseudo-pixel 30 and detecting reactive illumination light.

Further, it is possible to utilize pseudo-pixels for automation ofquality evaluation of the display device by installing another wiring toexamine a layer with a part of pseudo-pixels 30.

FIG. 5 shows third exemplary embodiment. The same reference numbersshown in FIG. 3 are referred to in FIG. 5 and explanation of them isomitted.

In this example, the hydrophilic control layer 60 is not arranged. Inaddition, the ITO layer 59 is installed in the pseudo-pixel 30. The ITOlayer 59 in the part of the pseudo-pixel 30 is insulated fromcircumference. Even under this structure, the condition of a luminescentelement of the effective pixel 20 is the same condition of a luminescentelement of the pseudo-pixel 30 so that it is possible to determine theuniformity of a formed layer by examining the layer of the luminescentelement of the pseudo-pixel 30.

FIG. 6 shows a fourth exemplary embodiment. In this example, the region3 of the pseudo-pixels 30 is formed in the left and the right side ofthe effective display pixel region 2. When a material to form a layer iscoated on the substrate by moving the inkjet head (not shown in FIG. 6)to the left and right direction repeatedly, such arrangement of thepseudo-pixels may be appropriate.

FIG. 7 shows a fifth exemplary embodiment. In this example, the region 3of the pseudo-pixel 30 is formed in the top and the bottom side of theeffective display pixel region 2. When a material to form a layer iscoated on the substrate by moving the inkjet head (not shown in FIG. 7)to the top and bottom direction repeatedly, such arrangement of thepseudo-pixels may be appropriate.

Some examples of electronic apparatus provided with a display device ofthe present invention are described below. But, application is notlimited to these examples.

Mobile Type Computer

First, an example where a display device of the above-mentionedexemplary embodiment is applied to a mobile type personal computer isdescribed. FIG. 8 is a perspective view showing a personal computer. InFIG. 8, a personal computer 1100 includes a main body portion 1104provided with a keyboard 1102, and a display device unit provided with adisplay device 1106 described above (it is equivalent to the displaydevice 1 in FIG. 1).

Cellular Phone

Next, an example where a display device of the above mentioned exemplaryembodiment is applied to a display portion for a cellular phone. FIG. 9is a perspective view of a cellular phone. In FIG. 9, a cellular phone1200 includes plural operation buttons 1202, an earpiece 1024, amouthpiece 1206 and an above mentioned display device 1208.

Digital Still Camera

A digital still camera provided with a finder including the displaydevice related to the above mentioned exemplary embodiment is described.FIG. 10 is a perspective view showing a digital still camera and aconnection to outside equipment.

In a conventional camera, film is exposed to an optical image of asubject. On the other hand, in the digital still camera 1300, an opticalimage of a subject is converted into image pick up signals with opticelectrical conversion by a image pick up elements, such as CCD (ChargeCoupled Device). On the back side of a case 1302 of the digital stillcamera 1300, the above mentioned display device 1304 is installed so asto display an image in response to an image signal from the CCD. Hence,the display device 1304 functions as a finder displaying a subject. Inaddition, on the observation side of the case 1302 (the back side inFIG. 10), a light receiving unit including optics lens or the CCD isinstalled.

When a photographer pushes a shutter button 1308 after confirming animage of a subject displayed by the display device 1304, image pick upsignals at that time are transferred to a memory in a circuit board 1310and stored in it. In addition, this digital still camera 1300 isprovided with a video signal output terminal 1312 and input and outputterminals 1314 at the side of the case 1302. As shown in FIG. 10, a TVmonitor 1430 is connected to the video signal output terminal 1312 and apersonal computer 1430 is connected to the input and output terminal1314, if it is necessary. Further, image pick up signals stored in amemory of the circuit board 1308 is outputted to the TV monitor 1330 andthe personal computer 1340.

Electronic Book

FIG. 11 is a perspective view showing an electronic book as an exampleof electronic apparatus of the present invention. In FIG. 11, referencenumber 1400 corresponds to the electronic book. The electronic book 1400includes a book style frame 1402 and a cover 1403 that can be opened orclosed to this frame 1402. In the frame 1402, a display portion 1404 isinstalled with exposing its surface and an operation portion 1405 isalso installed. In the inside of the frame 1402, a controller, acounter, and a memory are installed. According to the present exemplaryembodiment, the display device 1404 is provided with pixel portionsformed by filling electronic ink to a thin film element and a peripheralintegrated circuit formed with being integrated with this pixel portion.A peripheral circuit is provided with a decoder-type scan driver and adata driver.

Further, as electronic apparatus, in addition to a personal computer ofFIG. 8, the digital still camera of FIG. 10, and the electronic book ofFIG. 11, electronic paper, a liquid crystal television, a view findertype or a monitor direct view type video recorder, a navigation systemfor an automobile, a pager, an electronic note, an electroniccalculator, a word processor, a work station, a TV phone, a POSterminal, an apparatus with a touch panel can be used, for example. Theabove mentioned display device can be applied to these and otherelectronic apparatus.

When the above mentioned display device is installed in theabove-mentioned electronic apparatus, sight recognition of an imagedisplayed on a display portion can be deteriorated depending on a body'scolor. For example, when a body color is white, silver, or reflection orluster nature, and the border portion between a display and a body showsthe same colors, such as white or silver, a border portion between adisplay and a body happens to be blurred. In such case, if a coloredregion, of which color is different from a body's color or showssufficient contrast against it, is installed in the dummy pixel region,sight recognition of an image shown in a display portion can beenhanced, whereas any colors are displayed in a display portion.

In the case of a so-called back emission type where light emitted fromthe organic EL layer 63 is taken out from the side of the substrate 51,a coloration material may be attached at the backside of the substrate51.

In the case of a so-called top emission type where light emitted fromthe organic EL layer 63 is taken out from the side of common electrode(in the above exemplary embodiment, the cathode 64 is referred to as thecommon electrode), a color region may be installed on the commonelectrode or the cathode 64 may be replaced with a color region.

In addition, an illumination region that emits color light, which isdifferent from body's color, may be provided with supplying electricpower to a pixel in a dummy pixels area via a pixel electrode.

EFFECTS OF THE INVENTION

As discussed above, the display device of the present invention isprovided with pseudo-pixels arranged in the region that is adjacent tothe region of effective display pixels, enabling the starting and endingof ejection of a material to form a layer in the region includingpseudo-pixels by an inkjet method. Hence, forming a layer withuniformity can be easily attained in the effective display region.

1. An electro-optical device, comprising: a substrate; a plurality ofpixels disposed above the substrate, the plurality of pixels including agroup of pixels drivable to display information within an effectivedisplay region, and a group of plural pseudo-pixels, that do notcontribute to the display of information, located adjacent to theeffective display region; and a data line drive circuit that at leastpartially overlaps the group of plural pseudo-pixels.
 2. Theelectro-optical device according to claim 1, the group of pluralpseudo-pixels being located at least on one side of the effectivedisplay region.
 3. The electro-optical device according to claim 1, thegroup of plural pseudo-pixels being located surrounding the effectivedisplay region.
 4. The electro-optical device according to claim 1, thegroup of pixels within the effective display region including structuralelements, at least one of the structural elements including a functionallayer that is formed by an inkjet method.
 5. The electro-optical deviceaccording to claim 4, the at least one structural element formed by theinkjet method being an organic EL layer.
 6. The electro-optical deviceaccording to claim 5, the organic EL layer being made of a high polymermaterial.
 7. The electro-optical device according to claim 1, the shapeof the group of pixels in the effective display region being almost sameas the shape of the group of plural pseudo-pixels.
 8. An electro-opticaldevice, comprising: a substrate; a plurality of pixels disposed abovethe substrate, the plurality of pixels including a group of pixelsdrivable to display information within an effective display region, anda group of plural pseudo-pixels that do not contribute to the display ofinformation located adjacent to the effective display region; and ascanning line drive circuit that at least partially overlaps the groupof plural pseudo-pixels.